The EU-funded CHAiRLIFT project plans to assess an innovative combustor designed for next-generation lean-burn engines. In this new combustor, the lifted spray flames will feature a high degree of premixing, which will result in significantly reduced NOx emissions. Compared with conventional swirl stabilised flames, lifted spray flames strongly minimise the risk of combustor flame flashback and reduce susceptibility to thermoacoustics instabilities. The project will also propose an alternative approach to standard flame piloting, thereby enabling further reductions in NOx emissions. Experimental and numerical investigations including the development of an advanced spray atomisation model will be carried out to assess the NOx reduction capabilities of the new combustor.
The main objective of the CHAiRLIFT project is to assess an innovative combustor concept capable to achieve an ultra-lean, low NOx, operation of future engines. With this combustion concept the requirements of ACARE Flightpath 2050 will be fully satisfied. The CHAiRLIFT combustor concept comprises two novel features: The first is to adopt “low swirl” lean lifted spray flames which feature a high degree of premixing and consequently significantly reduced NOx emissions. Inherent characteristics of such flames are the strongly reduced risk of flashback and a reduced susceptibility to thermo-acoustics instabilities compared to conventional swirl stabilized flames. However, such lifted flames bear the risk of lean blow out at some operating conditions. As second novelty of the CHAiRLIFT concept an alternative approach to standard flame piloting is proposed, enabling a a further reduction of NOx emissions. Stable and safe operations of the combustor are ensured by the interaction of adjacent flames in circumferential direction within the annular combustion chamber. This requires tilting of the axis of the flames relative to the axis of the machine. This design is called Short Helical Combustor (SHC). It has the advantage that no extra pilot flame is required which may produce additional NOx emissions. Additional benefits are the reduced length of the combustor. Most importantly, the turning angle of the NGV can be reduced resulting into a smaller number of NGV and hence reduced cooling air requirement.
Experimental and numerical investigations including the development of an advanced spray atomization model will be carried to assess the NOx reduction capabilities of the concept, by exploiting state of the art methodologies. To explore further NOx reduction capabilities of the concept, an advanced LBO active control will also be tested by combining ion sensor probe and plasma assisted combustion.